The present invention relates to a hollow building block having one or a plurality of chambers distributed throughout the block. The chambers are open on at least one side and filled entirely or in part with foamed plastics which are anchored within the chamber walls. The invention further relates to a method for producing such hollow building blocks as well as to apparatus for manufacturing the blocks.
It is known to use hollow blocks to build walls, particularly sound and heat insulating walls. These blocks, which are of different sizes and made of various materials, usually have a plurality of regularly arranged chambers provided therein. The walls of the chambers are parallel to the outer walls of the block and the chambers generally extend within the interior of the block from load-bearing face to load-bearing face. The blocks are frequently made of grains of pumice stone which are bound together by means of cement. They may also be made of sand-lime bricks or other suitable materials such as clay or clay-containing masses which are molded and then hardened by firing.
The chambers penetrating the block lead to a significant savings in material and weight without substantially reducing the strength of the block. Moreover, due to the enclosed air spaces, the chambers cause the heat dissipation capability of the total block to be reduced and consequently its insulating capacity to be increased.
It is known to improve the heat and particularly the sound insulating capability of such blocks by filling the chamber cavities with heat or sound damping insulating material, as disclosed in German Pat. No. 1,708,765. The material may be, for example, a compact, foamed substance of synthetic resin which is attached tightly to the chamber walls by pressing prefabricated foamed pieces into the blocks or by foaming in the substance without the formation of cavities. The improvement in the heat and sound insulating properties obtained with such insulating fills, particularly foamed fills, is considerable.
However, blocks filled with such compact foamed material are disadvantageous in that their gas or vapor permeability is greatly reduced compared to unfilled hollow building blocks. Consequently, condensate is formed in the wall structure of such blocks, particularly as a result of the accumulation of moisture. Comparative measurements have shown that the vapor diffusion resistance factor, which for commercially available hollow building blocks of cement-bound pumice lies between 5 and 10, increases to from 40 to 140, with an average of about 70, when compact foamed polystyrene plates are built in. This means that the diffusion resistance is less favorable by a factor of about 10.
It is an object of the present invention to provide apparatus for producing a building block whose heat insulating capability is increased as compared to a conventional, unfilled hollow building blocks of the same material but without the gas or vapor diffusion factor being significantly impaired.